udhcpc: support for -O <option>.

Two important notes:
* nissrv and nisdomain are not requested by default anymore!
* inconsistency between "XXXsvr" and "XXsrv" in option names resolved,
  all are "XXXsrv" now.

function                                             old     new   delta
udhcpc_main                                         2494    2600    +106
packed_usage                                       23023   23067     +44
add_requests                                          91     119     +28
static.udhcpc_longopts                               209     226     +17
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 4/0 up/down: 195/0)             Total: 195 bytes

1 files changed, 3 insertions, 1 deletions

diff --git a/include/usage.h b/include/usage.h
index f6506b4f8..12d2cefd9 100644
--- a/include/usage.h
+++ b/include/usage.h
@@ -3840,7 +3840,7 @@ USE_FEATURE_RUN_PARTS_FANCY("\n	-l	Prints names of all matching files even when
 
 #define udhcpc_trivial_usage \
        "[-Cfbnqtv] [-c CID] [-V VCLS] [-H HOSTNAME] [-i INTERFACE]\n" \
-       "        [-p pidfile] [-r IP] [-s script]"
+       "        [-p pidfile] [-r IP] [-s script] [-O dhcp-option]..."
 #define udhcpc_full_usage \
         USE_GETOPT_LONG( \
        "        -V,--vendorclass=CLASSID        Vendor class identifier" \
@@ -3860,6 +3860,7 @@ USE_FEATURE_RUN_PARTS_FANCY("\n	-l	Prints names of all matching files even when
        "\n      -n,--now        Exit with failure if lease is not immediately obtained" \
        "\n      -q,--quit       Quit after obtaining lease" \
        "\n      -R,--release    Release IP on quit" \
+       "\n      -O,--request-option=OPT Request DHCP option OPT from server" \
         USE_FEATURE_UDHCPC_ARPING( \
        "\n      -a,--arping     Use arping to validate offered address" \
         ) \
@@ -3882,6 +3883,7 @@ USE_FEATURE_RUN_PARTS_FANCY("\n	-l	Prints names of all matching files even when
        "\n      -n              Exit with failure if lease is not immediately obtained" \
        "\n      -q              Quit after obtaining lease" \
        "\n      -R              Release IP on quit" \
+       "\n      -O OPT          Request DHCP option OPT from server" \
         USE_FEATURE_UDHCPC_ARPING( \
        "\n      -a              Use arping to validate offered address" \
         ) \